Colleagues of mine (a married couple) from New Zealand were in Seminyak for Nyepi Day. She was expecting and felt ill and wanted to go to hospital. Hotel staff made things difficult and in fact lied. It took 2 hours for them to be able to finally leave the hotel but got to hospital very fast. She lost her baby.
I've been to Bali many times and will continue to come. I was in Sanur at the time. I thought Nyepi Day was very interesting especially with Ogo Ogo the day before.
But the Balinese need to be more prepared for legitimate emergencies arising on Nyepi Day especially with tourists from a far away land.